/*
 * @(#)AVA.java	1.35 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package sun.security.x509;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Reader;

import java.util.Map;
import java.util.HashMap;
import java.util.ArrayList;

import java.util.Locale;
import sun.text.Normalizer;

import sun.security.util.*;
import sun.security.pkcs.PKCS9Attribute;


/**
 * X.500 Attribute-Value-Assertion (AVA):  an attribute, as identified by
 * some attribute ID, has some particular value.  Values are as a rule ASN.1
 * printable strings.  A conventional set of type IDs is recognized when
 * parsing (and generating) RFC 1779 or RFC 2253 syntax strings.
 *
 * <P>AVAs are components of X.500 relative names.  Think of them as being
 * individual fields of a database record.  The attribute ID is how you
 * identify the field, and the value is part of a particular record.
 * <p>
 * Note that instances of this class are immutable.
 *
 * @see X500Name
 * @see RDN
 *
 * @version 1.35, 10/10/06
 *
 * @author David Brownell
 * @author Amit Kapoor
 * @author Hemma Prafullchandra
 */
public class AVA implements DerEncoder {

    private static final Debug debug = Debug.getInstance("x509", "\t[AVA]");

    /**
     * DEFAULT format allows both RFC1779 and RFC2253 syntax and
     * additional keywords.
     */
    final static int DEFAULT = 1;
    /**
     * RFC1779 specifies format according to RFC1779.
     */
    final static int RFC1779 = 2;
    /**
     * RFC2253 specifies format according to RFC2253.
     */
    final static int RFC2253 = 3;

    // currently not private, accessed directly from RDN
    final ObjectIdentifier oid;
    final DerValue value;

    /*
     * If the value has any of these characters in it, it must be quoted.
     * Backslash and quote characters must also be individually escaped.
     * Leading and trailing spaces, also multiple internal spaces, also
     * call for quoting the whole string.
     */
    private static final String specialChars = ",+=\n<>#;";
    
    /*
     * In RFC2253, if the value has any of these characters in it, it
     * must be quoted by a preceding \.
     */
    private static final String specialChars2253 = ",+\"\\<>;";

    /*
     * includes special chars from RFC1779 and RFC2253, as well as ' '
     */
    private static final String specialCharsAll = ",=\n+<>#;\\\" ";

    /*
     * Values that aren't printable strings are emitted as BER-encoded
     * hex data.
     */
    private static final String hexDigits = "0123456789ABCDEF";

    public AVA(ObjectIdentifier type, DerValue val) {
	if ((type == null) || (val == null)) {
	    throw new NullPointerException();
	}
	oid = type;
	value = val;
    }

    /**
     * Parse an RFC 1779 or RFC 2253 style AVA string:  CN=fee fie foe fum
     * or perhaps with quotes.  Not all defined AVA tags are supported;
     * of current note are X.400 related ones (PRMD, ADMD, etc).
     *
     * This terminates at unescaped AVA separators ("+") or RDN
     * separators (",", ";"), or DN terminators (">"), and removes
     * cosmetic whitespace at the end of values.
     */
    AVA(Reader in) throws IOException {
        this(in, DEFAULT);
    }
    
    /**
     * Parse an AVA string formatted according to format.
     *
     * NOTE: format RFC1779 should only allow RFC1779 syntax but is
     * actually DEFAULT with RFC1779 keywords.
     */
    AVA(Reader in, int format) throws IOException {
        // assume format is one of DEFAULT, RFC1779, RFC2253
     
	StringBuffer	temp = new StringBuffer();
	int		c;

	/*
	 * First get the keyword indicating the attribute's type,
	 * and map it to the appropriate OID.
	 */
	while (true) {
	    c = readChar(in, "Incorrect AVA format");
	    if (c == '=') {
		break;
	    }
	    temp.append((char)c);
	}

	oid = AVAKeyword.getOID(temp.toString(), format);

	/*
	 * Now parse the value.  "#hex", a quoted string, or a string
	 * terminated by "+", ",", ";", ">".  Whitespace before or after
	 * the value is stripped away unless format is RFC2253.
	 */
	temp.setLength(0);
	if (format == RFC2253) {
	    // read next character
	    c = in.read();
	    if (c == ' ') {
		throw new IOException("Incorrect AVA RFC2253 format - " +
					"leading space must be escaped");
	    }
	} else {
	    // read next character skipping whitespace
	    do {
	        c = in.read();
	    } while ((c == ' ') || (c == '\n'));
	}
        if (c == -1) {
	    // empty value
	    value = new DerValue("");
	    return;
	}

	if (c == '#') {
	    value = parseHexString(in, format);
	} else if ((c == '"') && (format != RFC2253)) {
	    value = parseQuotedString(in, temp);
	} else {
	    value = parseString(in, c, format, temp);
	}
    }
    
    /**
     * Get the ObjectIdentifier of this AVA.
     */
    public ObjectIdentifier getObjectIdentifier() {
	return oid;
    }
    
    /**
     * Get the value of this AVA as a DerValue.
     */
    public DerValue getDerValue() {
	return value;
    }
    
    /**
     * Get the value of this AVA as a String.
     *
     * @exception RuntimeException if we could not obtain the string form
     *    (should not occur)
     */
    public String getValueString() {
	try {
	    String s = value.getAsString();
	    if (s == null) {
		throw new RuntimeException("AVA string is null");
	    }
	    return s;
	} catch (IOException e) {
	    // should not occur
	    throw new RuntimeException("AVA error: " + e, e);
	}
    }

    private static DerValue parseHexString
	(Reader in, int format) throws IOException {

	int c;
	ByteArrayOutputStream baos = new ByteArrayOutputStream();
	byte b = 0;
	int cNdx = 0;
	while (true) {
	    c = in.read();
		
	    if (isTerminator(c, format)) {
		break;
	    }

	    int cVal = hexDigits.indexOf(Character.toUpperCase((char)c));

	    if (cVal == -1) {
		throw new IOException("AVA parse, invalid hex " +
					      "digit: "+ (char)c);
	    }

	    if ((cNdx % 2) == 1) {
		b = (byte)((b * 16) + (byte)(cVal));
		baos.write(b);
	    } else {
		b = (byte)(cVal);
	    }
	    cNdx++;
	}

	// throw exception if no hex digits
	if (cNdx == 0) {
	    throw new IOException("AVA parse, zero hex digits");
	}

	// throw exception if odd number of hex digits
	if (cNdx % 2 == 1) {
	    throw new IOException("AVA parse, odd number of hex digits");
	}

	return new DerValue(baos.toByteArray());
    }

    private DerValue parseQuotedString
	(Reader in, StringBuffer temp) throws IOException {

	// RFC1779 specifies that an entire RDN may be enclosed in double 
	// quotes. In this case the syntax is any sequence of 
        // backslash-specialChar, backslash-backslash,
	// backslash-doublequote, or character other than backslash or
	// doublequote.
	int c = readChar(in, "Quoted string did not end in quote");

	ArrayList embeddedHex = new ArrayList();
	boolean isPrintableString = true;
	while (c != '"') {
	    if (c == '\\') {
		c = readChar(in, "Quoted string did not end in quote");

		// check for embedded hex pairs
		Byte hexByte = null;
		if ((hexByte = getEmbeddedHexPair(c, in)) != null) {

		    // always encode AVAs with embedded hex as UTF8
		    isPrintableString = false;

		    // append consecutive embedded hex
		    // as single string later
		    embeddedHex.add(hexByte);
		    c = in.read();
		    continue;
		}

		if (c != '\\' && c != '"' &&
		    specialChars.indexOf((char)c) < 0) {
		    throw new IOException
			("Invalid escaped character in AVA: " +
			(char)c);
		}
	    } 

	    // add embedded hex bytes before next char
	    if (embeddedHex.size() > 0) {
		String hexString = getEmbeddedHexString(embeddedHex);
		temp.append(hexString);
		embeddedHex.clear();
	    }
		
	    // check for non-PrintableString chars
	    isPrintableString &= DerValue.isPrintableStringChar((char)c);
	    temp.append((char)c);
	    c = readChar(in, "Quoted string did not end in quote");
	}

	// add trailing embedded hex bytes
	if (embeddedHex.size() > 0) {
	    String hexString = getEmbeddedHexString(embeddedHex);
	    temp.append(hexString);
	    embeddedHex.clear();
	}
		
	do {
	    c = in.read();
	} while ((c == '\n') || (c == ' '));
	if (c != -1) {
	    throw new IOException("AVA had characters other than "
		    + "whitespace after terminating quote");
	}

	// encode as PrintableString unless value contains
	// non-PrintableString chars
	if (this.oid.equals(PKCS9Attribute.EMAIL_ADDRESS_OID)) {
	    // EmailAddress must be IA5String
	    return new DerValue(DerValue.tag_IA5String,
					temp.toString().trim());
	} else if (isPrintableString) {
	    return new DerValue(temp.toString().trim());
	} else {
	    return new DerValue(DerValue.tag_UTF8String,
					temp.toString().trim());
	}
    } 

    private DerValue parseString
	(Reader in, int c, int format, StringBuffer temp) throws IOException {

	ArrayList embeddedHex = new ArrayList();
	boolean isPrintableString = true;
	boolean escape = false;
	boolean leadingChar = true;
	int spaceCount = 0;
	do {
	    escape = false;
	    if (c == '\\') {
		escape = true;
		c = readChar(in, "Invalid trailing backslash");

		// check for embedded hex pairs
		Byte hexByte = null;
		if ((hexByte = getEmbeddedHexPair(c, in)) != null) {

		    // always encode AVAs with embedded hex as UTF8
		    isPrintableString = false;

		    // append consecutive embedded hex
		    // as single string later
		    embeddedHex.add(hexByte);
		    c = in.read();
		    leadingChar = false;
		    continue;
		}

		// check if character was improperly escaped
		if ((format == DEFAULT &&
			specialCharsAll.indexOf((char)c) == -1) ||
		    (format == RFC1779  &&
			specialChars.indexOf((char)c) == -1 &&
			c != '\\' && c != '\"')) {

		    throw new IOException
			("Invalid escaped character in AVA: '" +
			(char)c + "'");

		} else if (format == RFC2253) {
		    if (c == ' ') {
			// only leading/trailing space can be escaped
			if (!leadingChar && !trailingSpace(in)) {
				throw new IOException
					("Invalid escaped space character " +
					"in AVA.  Only a leading or trailing " +
					"space character can be escaped.");
			}
		    } else if (c == '#') {
			// only leading '#' can be escaped
			if (!leadingChar) {
			    throw new IOException
				("Invalid escaped '#' character in AVA.  " +
				"Only a leading '#' can be escaped.");
			}
		    } else if (specialChars2253.indexOf((char)c) == -1) {
			throw new IOException
				("Invalid escaped character in AVA: '" +
				(char)c + "'");

		    }
		}

	    } else {
		// check if character should have been escaped
		if (format == RFC2253) {
		    if (specialChars2253.indexOf((char)c) != -1) {
			throw new IOException
				("Character '" + (char)c +
				"' in AVA appears without escape");
		    }
		}
	    }

	    // add embedded hex bytes before next char
	    if (embeddedHex.size() > 0) {
		// add space(s) before embedded hex bytes
		for (int i = 0; i < spaceCount; i++) {
		    temp.append(" ");
		}
		spaceCount = 0;

		String hexString = getEmbeddedHexString(embeddedHex);
		temp.append(hexString);
		embeddedHex.clear();
	    }
		
	    // check for non-PrintableString chars
	    isPrintableString &= DerValue.isPrintableStringChar((char)c);
	    if (c == ' ' && escape == false) {
		// do not add non-escaped spaces yet
		// (non-escaped trailing spaces are ignored)
		spaceCount++;
	    } else {
		// add space(s)
		for (int i = 0; i < spaceCount; i++) {
		    temp.append(" ");
		}
		spaceCount = 0;
		temp.append((char)c);
	    }
	    c = in.read();
	    leadingChar = false;
	} while (isTerminator(c, format) == false);

	if (format == RFC2253 && spaceCount > 0) {
	    throw new IOException("Incorrect AVA RFC2253 format - " +
					"trailing space must be escaped");
	}

	// add trailing embedded hex bytes
	if (embeddedHex.size() > 0) {
	    String hexString = getEmbeddedHexString(embeddedHex);
	    temp.append(hexString);
	    embeddedHex.clear();
	}
		
	// encode as PrintableString unless value contains
	// non-PrintableString chars
	if (this.oid.equals(PKCS9Attribute.EMAIL_ADDRESS_OID)) {
	    // EmailAddress must be IA5String
	    return new DerValue(DerValue.tag_IA5String, temp.toString());
	} else if (isPrintableString) {
	    return new DerValue(temp.toString());
	} else {
	    return new DerValue(DerValue.tag_UTF8String, temp.toString());
	}
    }

    private static Byte getEmbeddedHexPair(int c1, Reader in)
	throws IOException {

	if (hexDigits.indexOf(Character.toUpperCase((char)c1)) >= 0) {
	    int c2 = readChar(in, "unexpected EOF - " +
			"escaped hex value must include two valid digits");

	    if (hexDigits.indexOf(Character.toUpperCase((char)c2)) >= 0) {
		int hi = Character.digit((char)c1, 16);
		int lo = Character.digit((char)c2, 16);
		return new Byte((byte)((hi<<4) + lo));
	    } else {
		throw new IOException
			("escaped hex value must include two valid digits");
	    }
	}
	return null;
    }

    private static String getEmbeddedHexString(ArrayList hexList)
						throws IOException {
	byte[] hexBytes = new byte[hexList.size()];
	for (int i = 0; i < hexList.size(); i++) {
		hexBytes[i] = ((Byte)hexList.get(i)).byteValue();
	}
	return new String(hexBytes, "UTF8");
    }

    private static boolean isTerminator(int ch, int format) {
        switch (ch) {
	case -1:
	case '+':
	case ',':
	    return true;
	case ';':
	case '>':
	    return format != RFC2253;
	default:
	    return false;
	}
    }

    private static int readChar(Reader in, String errMsg) throws IOException {
	int c = in.read();
	if (c == -1) {
	    throw new IOException(errMsg);
	}
	return c;
    }

    private static boolean trailingSpace(Reader in) throws IOException {

	boolean trailing = false;

	if (!in.markSupported()) {
	    // oh well
	    return true;
	} else {
	    // make readAheadLimit huge -
	    // in practice, AVA was passed a StringReader from X500Name,
	    // and StringReader ignores readAheadLimit anyways
	    in.mark(9999);
	    while (true) {
		int nextChar = in.read();
		if (nextChar == -1) {
		    trailing = true;
		    break;
		} else if (nextChar == ' ') {
		    continue;
		} else if (nextChar == '\\') {
		    int followingChar = in.read();
		    if (followingChar != ' ') {
			trailing = false;
			break;
		    }
		} else {
		    trailing = false;
		    break;
		}
	    }

	    in.reset();
	    return trailing;
	}
    }

    AVA(DerValue derval) throws IOException {
	// Individual attribute value assertions are SEQUENCE of two values.
	// That'd be a "struct" outside of ASN.1.
	if (derval.tag != DerValue.tag_Sequence) {
	    throw new IOException("AVA not a sequence");
	}
	oid = X500Name.intern(derval.data.getOID());
	value = derval.data.getDerValue();

	if (derval.data.available() != 0) {
	    throw new IOException("AVA, extra bytes = "
		+ derval.data.available());
	}
    }

    AVA(DerInputStream in) throws IOException {
	this(in.getDerValue());
    }

    public boolean equals(Object obj) {
	if (this == obj) {
	    return true;
	}
	if (obj instanceof AVA == false) {
	    return false;
	}
	AVA other = (AVA)obj;
	return this.toRFC2253CanonicalString().equals
				(other.toRFC2253CanonicalString());
    }

    /**
     * Returns a hashcode for this AVA.
     *
     * @return a hashcode for this AVA.
     */
    public int hashCode() {
	return toRFC2253CanonicalString().hashCode();
    }

    /*
     * AVAs are encoded as a SEQUENCE of two elements.
     */
    public void encode(DerOutputStream out) throws IOException {
	derEncode(out);
    }

    /**
     * DER encode this object onto an output stream.
     * Implements the <code>DerEncoder</code> interface.
     *
     * @param out
     * the output stream on which to write the DER encoding.
     *
     * @exception IOException on encoding error.
     */
    public void derEncode(OutputStream out) throws IOException {
	DerOutputStream		tmp = new DerOutputStream();
	DerOutputStream		tmp2 = new DerOutputStream();

	tmp.putOID(oid);
	value.encode(tmp);
	tmp2.write(DerValue.tag_Sequence, tmp);
	out.write(tmp2.toByteArray());
    }
    
    private String toKeyword(int format) {
        return AVAKeyword.getKeyword(oid, format);
    }

    /**
     * Returns a printable form of this attribute, using RFC 1779
     * syntax for individual attribute/value assertions.
     */
    public String toString() {
	return toKeywordValueString(toKeyword(DEFAULT));
    }

    /**
     * Returns a printable form of this attribute, using RFC 1779
     * syntax for individual attribute/value assertions. It only
     * emits standardised keywords.
     */
    public String toRFC1779String() {
	return toKeywordValueString(toKeyword(RFC1779));
    }

    /**
     * Returns a printable form of this attribute, using RFC 2253
     * syntax for individual attribute/value assertions. It only
     * emits standardised keywords.
     */
    public String toRFC2253String() {
	/*
	 * Section 2.3: The AttributeTypeAndValue is encoded as the string 
	 * representation of the AttributeType, followed by an equals character 
	 * ('=' ASCII 61), followed by the string representation of the 
	 * AttributeValue. The encoding of the AttributeValue is given in 
	 * section 2.4.
	 */
	StringBuffer typeAndValue = new StringBuffer(100);
	typeAndValue.append(toKeyword(RFC2253));
	typeAndValue.append('=');

	/*
	 * Section 2.4: Converting an AttributeValue from ASN.1 to a String.
   	 * If the AttributeValue is of a type which does not have a string
   	 * representation defined for it, then it is simply encoded as an
   	 * octothorpe character ('#' ASCII 35) followed by the hexadecimal
   	 * representation of each of the bytes of the BER encoding of the X.500
   	 * AttributeValue.  This form SHOULD be used if the AttributeType is of
   	 * the dotted-decimal form.
	 */
	if ((typeAndValue.charAt(0) >= '0' && typeAndValue.charAt(0) <= '9') ||
	    !isDerString(value, false)) 
	{
	    byte[] data = null;
	    try {
                data = value.toByteArray();
	    } catch (IOException ie) {
		throw new IllegalArgumentException("DER Value conversion");
	    }
            typeAndValue.append('#');
            for (int j = 0; j < data.length; j++) {
                byte b = data[j];
                typeAndValue.append(Character.forDigit(0xF & (b >>> 4), 16));
                typeAndValue.append(Character.forDigit(0xF & b, 16));
            }
	} else {
	    /*
	     * 2.4 (cont): Otherwise, if the AttributeValue is of a type which 
	     * has a string representation, the value is converted first to a 
	     * UTF-8 string according to its syntax specification.
	     *
	     * NOTE: this implementation only emits DirectoryStrings of the
	     * types returned by isDerString().
	     */
	    String valStr = null;
	    try {
		valStr = new String(value.getDataBytes(), "UTF8");
	    } catch (IOException ie) {
		throw new IllegalArgumentException("DER Value conversion");
	    }

	    /* 
	     * 2.4 (cont): If the UTF-8 string does not have any of the 
	     * following characters which need escaping, then that string can be
	     * used as the string representation of the value.
	     *
	     *   o   a space or "#" character occurring at the beginning of the
             *       string
	     *   o   a space character occurring at the end of the string
    	     *   o   one of the characters ",", "+", """, "\", "<", ">" or ";"
	     *
	     * Implementations MAY escape other characters.
	     *
 	     * NOTE: this implementation also recognizes "=" and "#" as 
	     * characters which need escaping.
	     *
   	     * If a character to be escaped is one of the list shown above, then
	     * it is prefixed by a backslash ('\' ASCII 92).
	     *
   	     * Otherwise the character to be escaped is replaced by a backslash 
	     * and two hex digits, which form a single byte in the code of the
	     * character.
	     */
            final String escapees = ",=+<>#;\"\\";
	    StringBuffer sbuffer = new StringBuffer();

	    for (int i = 0; i < valStr.length(); i++) {
		char c = valStr.charAt(i);
		if (DerValue.isPrintableStringChar(c) ||
		    escapees.indexOf(c) >= 0) {

		    // escape escapees
		    if (escapees.indexOf(c) >= 0) {
			sbuffer.append('\\');
		    }

		    // append printable/escaped char
		    sbuffer.append(c);

		} else if (debug != null && Debug.isOn("ava")) {

		    // embed non-printable/non-escaped char
		    // as escaped hex pairs for debugging
		    byte[] valueBytes = null;
		    try {
			valueBytes = Character.toString(c).getBytes("UTF8");
		    } catch (IOException ie) {
			throw new IllegalArgumentException
					("DER Value conversion");
		    }
		    for (int j = 0; j < valueBytes.length; j++) {
			sbuffer.append('\\');
			char hexChar = Character.forDigit
				(0xF & (valueBytes[j] >>> 4), 16);
			sbuffer.append(Character.toUpperCase(hexChar));
			hexChar = Character.forDigit
				(0xF & (valueBytes[j]), 16);
			sbuffer.append(Character.toUpperCase(hexChar));
		    }
		} else {

		    // append non-printable/non-escaped char
		    sbuffer.append(c);
		}
	    }

	    char[] chars = sbuffer.toString().toCharArray();
	    sbuffer = new StringBuffer();

	    // Find leading and trailing whitespace.
	    int lead;   // index of first char that is not leading whitespace
	    for (lead = 0; lead < chars.length; lead++) {
		if (chars[lead] != ' ' && chars[lead] != '\r') {
		    break;
		}
	    }
	    int trail;  // index of last char that is not trailing whitespace
	    for (trail = chars.length - 1; trail >= 0; trail--) {
		if (chars[trail] != ' ' && chars[trail] != '\r') {
		    break;
		}
	    }

	    // escape leading and trailing whitespace
	    for (int i = 0; i < chars.length; i++) {
		char c = chars[i];
		if (i < lead || i > trail) {
		    sbuffer.append('\\');
		}
		sbuffer.append(c);
	    }
	    typeAndValue.append(sbuffer.toString());
	}
	return new String(typeAndValue);
    }

    public String toRFC2253CanonicalString() {
	/*
	 * Section 2.3: The AttributeTypeAndValue is encoded as the string 
	 * representation of the AttributeType, followed by an equals character 
	 * ('=' ASCII 61), followed by the string representation of the 
	 * AttributeValue. The encoding of the AttributeValue is given in 
	 * section 2.4.
	 */
	StringBuffer typeAndValue = new StringBuffer(40);
	typeAndValue.append(toKeyword(RFC2253));
	typeAndValue.append('=');

	/*
	 * Section 2.4: Converting an AttributeValue from ASN.1 to a String.
   	 * If the AttributeValue is of a type which does not have a string
   	 * representation defined for it, then it is simply encoded as an
   	 * octothorpe character ('#' ASCII 35) followed by the hexadecimal
   	 * representation of each of the bytes of the BER encoding of the X.500
   	 * AttributeValue.  This form SHOULD be used if the AttributeType is of
   	 * the dotted-decimal form.
	 */
	if ((typeAndValue.charAt(0) >= '0' && typeAndValue.charAt(0) <= '9') ||
	    !isDerString(value, true)) 
	{
	    byte[] data = null;
	    try {
                data = value.toByteArray();
	    } catch (IOException ie) {
		throw new IllegalArgumentException("DER Value conversion");
	    }
            typeAndValue.append('#');
            for (int j = 0; j < data.length; j++) {
                byte b = data[j];
                typeAndValue.append(Character.forDigit(0xF & (b >>> 4), 16));
                typeAndValue.append(Character.forDigit(0xF & b, 16));
            }
	} else {
	    /*
	     * 2.4 (cont): Otherwise, if the AttributeValue is of a type which 
	     * has a string representation, the value is converted first to a 
	     * UTF-8 string according to its syntax specification.
	     *
	     * NOTE: this implementation only emits DirectoryStrings of the
	     * types returned by isDerString().
	     */
	    String valStr = null;
	    try {
		valStr = new String(value.getDataBytes(), "UTF8");
	    } catch (IOException ie) {
		throw new IllegalArgumentException("DER Value conversion");
	    }

	    /* 
	     * 2.4 (cont): If the UTF-8 string does not have any of the 
	     * following characters which need escaping, then that string can be
	     * used as the string representation of the value.
	     *
	     *   o   a space or "#" character occurring at the beginning of the
             *       string
	     *   o   a space character occurring at the end of the string
	     *
    	     *   o   one of the characters ",", "+", """, "\", "<", ">" or ";"
	     *
   	     * If a character to be escaped is one of the list shown above, then
	     * it is prefixed by a backslash ('\' ASCII 92).
	     *
   	     * Otherwise the character to be escaped is replaced by a backslash 
	     * and two hex digits, which form a single byte in the code of the
	     * character.
	     */
            final String escapees = ",+<>;\"\\";
	    StringBuffer sbuffer = new StringBuffer();
	    boolean previousWhite = false;

	    for (int i = 0; i < valStr.length(); i++) {
		char c = valStr.charAt(i);

		if (DerValue.isPrintableStringChar(c) ||
		    escapees.indexOf(c) >= 0 ||
		    (i == 0 && c == '#')) {

		    // escape leading '#' and escapees
		    if ((i == 0 && c == '#') || escapees.indexOf(c) >= 0) {
			sbuffer.append('\\');
		    }

		    // convert multiple whitespace to single whitespace
		    if (!Character.isWhitespace(c)) {
			previousWhite = false;
			sbuffer.append(c);
		    } else {
			if (previousWhite == false) {
			    // add single whitespace
			    previousWhite = true;
			    sbuffer.append(c);
			} else {
			    // ignore subsequent consecutive whitespace
			    continue;
			}
		    }

		} else if (debug != null && Debug.isOn("ava")) {

		    // embed non-printable/non-escaped char
		    // as escaped hex pairs for debugging

		    previousWhite = false;

		    byte valueBytes[] = null;
		    try {
			valueBytes = Character.toString(c).getBytes("UTF8");
		    } catch (IOException ie) {
			throw new IllegalArgumentException
					("DER Value conversion");
		    }
		    for (int j = 0; j < valueBytes.length; j++) {
			sbuffer.append('\\');
			sbuffer.append(Character.forDigit
					(0xF & (valueBytes[j] >>> 4), 16));
			sbuffer.append(Character.forDigit
					(0xF & (valueBytes[j]), 16));
		    }
		} else {

		    // append non-printable/non-escaped char

		    previousWhite = false;
		    sbuffer.append(c);
		}
	    }

	    // remove leading and trailing whitespace from value
	    typeAndValue.append(sbuffer.toString().trim());
	}

	String canon = new String(typeAndValue);
	canon = canon.toUpperCase(Locale.US).toLowerCase(Locale.US);
	return Normalizer.normalize(canon, Normalizer.DECOMP_COMPAT, 0);
    }

    /*
     * Return true if DerValue can be represented as a String.
     */
    private static boolean isDerString(DerValue value, boolean canonical) {
	if (canonical) {
	    switch (value.tag) {
		case DerValue.tag_PrintableString:
		case DerValue.tag_UTF8String:
		    return true;
		default:
		    return false;
	    }
	} else {
	    switch (value.tag) {
		case DerValue.tag_PrintableString:
		case DerValue.tag_T61String:
		case DerValue.tag_IA5String:
		case DerValue.tag_GeneralString:
		case DerValue.tag_BMPString:
		case DerValue.tag_UTF8String:
		    return true;
		default:
		    return false;
	    }
	}
    }
    
    boolean hasRFC2253Keyword() {
        return AVAKeyword.hasKeyword(oid, RFC2253);
    }

    private String toKeywordValueString(String keyword) {
	/*
	 * Construct the value with as little copying and garbage
	 * production as practical.  First the keyword (mandatory),
	 * then the equals sign, finally the value.
	 */
	StringBuffer	retval = new StringBuffer(40);

	retval.append(keyword);
	retval.append("=");

	try {
	    String valStr = value.getAsString();

	    if (valStr == null) {

		// rfc1779 specifies that attribute values associated
		// with non-standard keyword attributes may be represented
		// using the hex format below.  This will be used only
		// when the value is not a string type

		byte	data [] = value.toByteArray();

		retval.append('#');
		for (int i = 0; i < data.length; i++) {
		    retval.append(hexDigits.charAt((data [i] >> 4) & 0x0f));
		    retval.append(hexDigits.charAt(data [i] & 0x0f));
		}

	    } else {

		boolean	quoteNeeded = false;
		StringBuffer sbuffer = new StringBuffer();
		boolean previousWhite = false;

		/*
		 * Special characters (e.g. AVA list separators) cause strings
		 * to need quoting, or at least escaping.  So do leading or
		 * trailing spaces, and multiple internal spaces.
		 */
		for (int i = 0; i < valStr.length(); i++) {
		    char c = valStr.charAt(i);
		    if (DerValue.isPrintableStringChar(c) ||
			specialChars.indexOf(c) >= 0) {

			// quote if leading whitespace or special chars
			if (!quoteNeeded &&
			    ((i == 0 && (c == ' ' || c == '\n')) ||
				specialChars.indexOf(c) >= 0)) {
			    quoteNeeded = true;
			}

			// quote if multiple internal whitespace
			if (!(c == ' ' || c == '\n')) {
			    // escape '"' and '\'
			    if (c == '"' || c == '\\') {
				sbuffer.append('\\');
			    }
			    previousWhite = false;
			} else {
			    if (!quoteNeeded && previousWhite) {
				quoteNeeded = true;
			    }
			    previousWhite = true;
			}

			sbuffer.append(c);

		    } else if (debug != null && Debug.isOn("ava")) {

			// embed non-printable/non-escaped char
			// as escaped hex pairs for debugging

			previousWhite = false;

			// embed escaped hex pairs
			byte[] valueBytes =
				Character.toString(c).getBytes("UTF8");
			for (int j = 0; j < valueBytes.length; j++) {
			    sbuffer.append('\\');
			    char hexChar = Character.forDigit
					(0xF & (valueBytes[j] >>> 4), 16);
			    sbuffer.append(Character.toUpperCase(hexChar));
			    hexChar = Character.forDigit
					(0xF & (valueBytes[j]), 16);
			    sbuffer.append(Character.toUpperCase(hexChar));
			}
		    } else {

			// append non-printable/non-escaped char

			previousWhite = false;
			sbuffer.append(c);
		    }
		}
		
		// quote if trailing whitespace
		if (sbuffer.length() > 0) {
		    char trailChar = sbuffer.charAt(sbuffer.length() - 1);
		    if (trailChar == ' ' || trailChar == '\n') {
			quoteNeeded = true;
		    }
		}

		// Emit the string ... quote it if needed
		if (quoteNeeded) {
		    retval.append("\"" + sbuffer.toString() + "\"");
		} else {
		    retval.append(sbuffer.toString());
		}
	    }
	} catch (IOException e) {
	    throw new IllegalArgumentException("DER Value conversion");
	}

	return retval.toString();
    }

}

/**
 * Helper class that allows conversion from String to ObjectIdentifier and
 * vice versa according to RFC1779, RFC2253, and an augmented version of
 * those standards.
 */
class AVAKeyword {

    private static final Map oidMap, keywordMap;

    private String keyword;
    private ObjectIdentifier oid;
    private boolean rfc1779Compliant, rfc2253Compliant;

    private AVAKeyword(String keyword, ObjectIdentifier oid, 
               boolean rfc1779Compliant, boolean rfc2253Compliant) {
        this.keyword = keyword;
	this.oid = oid;
	this.rfc1779Compliant = rfc1779Compliant;
	this.rfc2253Compliant = rfc2253Compliant;

	// register it
        oidMap.put(oid, this);
	keywordMap.put(keyword, this);
    }
    
    private boolean isCompliant(int standard) {
        switch (standard) {
	case AVA.RFC1779:
	    return rfc1779Compliant;
	case AVA.RFC2253:
	    return rfc2253Compliant;
	case AVA.DEFAULT:
	    return true;
	default:
	    // should not occur, internal error
	    throw new IllegalArgumentException("Invalid standard " + standard);
	}
    }
    
    /**
     * Get an object identifier representing the specified keyword (or
     * string encoded object identifier) in the given standard.
     *
     * @throws IOException If the keyword is not valid in the specified standard
     */    
    static ObjectIdentifier getOID(String keyword, int standard) 
	    throws IOException {
	keyword = keyword.toUpperCase();
	if (standard == AVA.RFC2253) {
	    if (keyword.startsWith(" ") || keyword.endsWith(" ")) {
	        throw new IOException("Invalid leading or trailing space " +
			"in keyword \"" + keyword + "\"");
	    }
	} else {
	    keyword = keyword.trim();
	}

        AVAKeyword ak = (AVAKeyword)keywordMap.get(keyword);
	if ((ak != null) && ak.isCompliant(standard)) {
	    return ak.oid;
	}

	// no keyword found or not standard compliant, check if OID string

	// RFC1779 requires, DEFAULT allows OID. prefix
	if (standard == AVA.RFC1779) {
	    if (keyword.startsWith("OID.") == false) {
	        throw new IOException("Invalid RFC1779 keyword: " + keyword);
	    }
	    keyword = keyword.substring(4);
	} else if (standard == AVA.DEFAULT) {
	    if (keyword.startsWith("OID.")) {
	        keyword = keyword.substring(4);
	    }
	}
	boolean number = false;
	if (keyword.length() != 0) {
	    char ch = keyword.charAt(0);
	    if ((ch >= '0') && (ch <= '9')) {
	        number = true;
	    }
	}
	if (number == false) {
	    throw new IOException("Invalid keyword \"" + keyword + "\"");
	}
	return new ObjectIdentifier(keyword);
    }

    /**
     * Get a keyword for the given ObjectIdentifier according to standard.
     * If no keyword is available, the ObjectIdentifier is encoded as a
     * String.
     */
    static String getKeyword(ObjectIdentifier oid, int standard) {
        AVAKeyword ak = (AVAKeyword)oidMap.get(oid);
	if ((ak != null) && ak.isCompliant(standard)) {
	    return ak.keyword;
	}
	// no compliant keyword, use OID
	String oidString = oid.toString();
	if (standard == AVA.RFC2253) {
	    return oidString;
	} else {
	    return "OID." + oidString;
	}
    }    
    
    /**
     * Test if oid has an associated keyword in standard.
     */
    static boolean hasKeyword(ObjectIdentifier oid, int standard) {
        AVAKeyword ak = (AVAKeyword)oidMap.get(oid);
	if (ak == null) {
	    return false;
	}
	return ak.isCompliant(standard);
    }

    static {
        oidMap = new HashMap();
	keywordMap = new HashMap();

        // NOTE if multiple keywords are available for one OID, order
	// is significant!! Preferred *LAST*.
        new AVAKeyword("CN",           X500Name.commonName_oid,   true,  true);
        new AVAKeyword("C",            X500Name.countryName_oid,  true,  true);
        new AVAKeyword("L",            X500Name.localityName_oid, true,  true);
        new AVAKeyword("S",            X500Name.stateName_oid,    false, false);
        new AVAKeyword("ST",           X500Name.stateName_oid,    true,  true);
        new AVAKeyword("O",            X500Name.orgName_oid,      true,  true);
        new AVAKeyword("OU",           X500Name.orgUnitName_oid,  true,  true);
        new AVAKeyword("T",            X500Name.title_oid,        false, false);
        new AVAKeyword("IP",           X500Name.ipAddress_oid,    false, false);
        new AVAKeyword("STREET",       X500Name.streetAddress_oid,true,  true);
        new AVAKeyword("DC",           X500Name.DOMAIN_COMPONENT_OID, 
	                                                          false, true);
        new AVAKeyword("DNQUALIFIER",  X500Name.DNQUALIFIER_OID,  false, false);
        new AVAKeyword("DNQ",          X500Name.DNQUALIFIER_OID,  false, false);
        new AVAKeyword("SURNAME",      X500Name.SURNAME_OID,      false, false);
        new AVAKeyword("GIVENNAME",    X500Name.GIVENNAME_OID,    false, false);
        new AVAKeyword("INITIALS",     X500Name.INITIALS_OID,     false, false);
        new AVAKeyword("GENERATION",   X500Name.GENERATIONQUALIFIER_OID, 
	                                                          false, false);
        new AVAKeyword("EMAIL", PKCS9Attribute.EMAIL_ADDRESS_OID, false, false);
        new AVAKeyword("EMAILADDRESS", PKCS9Attribute.EMAIL_ADDRESS_OID,
	                                                          false, false);
        new AVAKeyword("UID",          X500Name.userid_oid,       false, true);
	new AVAKeyword("SERIALNUMBER", X500Name.SERIALNUMBER_OID, false, false);
    }
}

